Docker notes

Pull

Pull in an image from the registry.

docker pull <imageName>:<tag>

Run

Run an image that has been downloaded with pull. Names the running image after the given --name argument.

docker run -t -d -p <hostPort>:<containerPort> --name <containerName> <imageName>

• -t allocates a pseudo terminal for the container
• -d detaches the process so that it runs in the background
• -p creates a host to container port mapping

Ps

List out the running containers.

docker ps

Exec

Execute on a running container.

docker exec -it <containerName> <programName>

(program name depends on the image, but common options are bash or sh)

• -it condenses -i allows interaction with the container, and -t which creates a pseudo terminal and displays it on your screen

Stop

Shutdown a container process.

docker stop <containerName>

Start

Start a previously stopped and idling container.

docker start <containerName>

Stats

Display stats on usage for memory, CPU, network etc. for each container.

docker stats

Why are docker containers so much faster than VMs?

The short answer is that docker containers can share the same kernel with the host operating system.